Start Exercising

It was a year on 8/26/12 that i had my LBS, i have already lost 70 lbs, but would like to lose about 50 more and tone up all of my fat. I have basically not exercised at all. So i decided i would get serious about getting into shape and losing the rest of the weight. I joined Title Boxing Club on tuesday. I love it!!! They have boxing and kickboxing classes, each class is 60 minutes long and very intense. They say that you can burn 1000 calories an hour. I have been to 2 boxing classes this week, they do a mixture of boxing, cardio and abs exercising. I know i am not burning the 1000 calories yet because half the stuff i cannot do, but i try. My questions is how often do you think i should exercise like this? I was thinking 3-4 times per week with a mix between the 2 types of classes. Right now i am very sore but that is becuase my body is rebeling (lol) but i know it will get better each time. I just want to get other opionions.

thanks,